The anchoring of industrial-scale machines in a concrete foundation which has been provided specifically for supporting and fastening the machine places high technical demands on the components responsible for distributing forces into the concrete foundation. The foundation anchor therefore needs to be able to ensure not only the appropriate distribution of force and securing during the normal operation of the machine but also sufficient fastening to ensure that the machine is anchored even in the event of malfunction. During such operation when there is a malfunction, owing to the unbalance forces occurring in the machine, malfunction-induced loads can be transmitted to the concrete foundation which are at least twice as great as the regular operating loads.
Industrial-scale machines should in the present case be understood in particular as machines in power plants. The following thus relates, for example, to foundation anchors of bearing housings on high-pressure turbines, medium-pressure turbines, and low-pressure turbines in a steam turbine power plant. However, for example individual machine parts can likewise require a corresponding anchoring, such as, for example, intercept valves of reheater tubes in industry-standard steam turbine power plants.
The industrial-scale machines are typically fastened in a fastening section of a foundation anchor by means of high-strength metal fastening bolts provided specifically for this purpose, so that a secure fastening to the concrete foundation can be achieved. The relevant fastening bolts can, for example, be screwed in a suitable fashion to a fastening nut which is surrounded by the foundation anchor. The load is transmitted to the foundation anchor in such a way that the forces occurring are distributed into the concrete foundation in a suitable fashion.
According to the internal prior devices known to the Applicant, to a steel construction is sometimes used for the foundation anchor, which initially distributes the forces which occur on the machine into two side plates manufactured from structural steel, wherein the two side plates are each connected to two welded-on crossbeams. The crossbeams are each rigidly connected to a number of suitably formed anchor rods so that the forces acting on the crossbeams can be distributed into the anchor rods. The anchor rods themselves are anchored non-positively in the concrete foundation so that the forces are directed into the concrete foundation.
However, it proves to be disadvantageous that the forces acting on the foundation anchor cannot be diverted into the concrete foundation without the forces being redirected. Because the side plates and crossbeams are connected at an angle, when forces are transmitted bending stresses occur in the area where the side plates and crossbeams are joined together which can be significantly increased. In particular in the event of operation when there is a malfunction, the forces acting on this joining area can exceed the strength of the connection, as a result of which an undesired failure, sometimes accompanied by serious consequences, can occur.
The technical proposal according to patent AT374531B attempts to overcome these disadvantages. This patent describes a device for anchoring supports in concrete foundations so that they are resistant tensile forces. The devices according to an embodiment of the invention has an anchor box for connection, for example, to a machine support and to the sides of which multiple connecting bars are welded. After the connecting bars have been embedded in a concrete foundation and when a load is applied to the device during operation, the forces which occur are diverted by the anchor box via the connecting bars along their axis of longitudinal extent into the concrete foundation. However, a disadvantage of this technical solution is that the devices need to be completely prefabricated before they are incorporated into the concrete foundation. The length and the weight of the connecting bars consequently entails a high degree of handling and transportation complexity. In addition, in order to ensure that forces are transmitted advantageously from the anchor box to the connecting bars, it is necessary to align the anchor box and connecting bars accurately. However, this alignment can only be achieved with great technical effort because two heavy and elongated components have to be welded together. Moreover, the high forces which need to be transmitted require the anchor box and connecting bars to be welded together very carefully, which cannot be performed on site when the device is being installed in a concrete foundation but typically needs to be carefully prefabricated in a factory.
There is therefore a technical need to propose an improved foundation anchor which is capable of overcoming the disadvantages as described above. In particular, it is intended for the proposed foundation anchor to be improved in terms of its manufacturing accuracy, ease of handling and ease of transportation. At the same time, it is intended that it is suitable for transmitting operating loads and malfunction-induced loads of an industrial-scale machine to a concrete foundation in a suitable fashion without there being any need to fear failure owing to excessive bending stresses.
Furthermore, it is intended for the foundation anchor to transmit forces as advantageously as possible into the concrete foundation, especially with the avoidance of secondary stresses.
It is likewise desirable to propose a foundation anchor which has an advantageous performance-to-weight ratio, i.e. it is intended that the ratio of failure-safe acceptable load to the total weight of the foundation anchor is advantageous. In addition, it is intended that the foundation anchor enables tolerances to be compensated when the industrial-scale machine is installed on the concrete foundation. It is intended in particular that this tolerance compensation allows both angular errors and positional errors to be compensated.